Kevin-Young
70cc twin V2
Jason, generally a canister or tuned pipe will shift the cg back a bit and make an airplane tail heavy.kork said
2robbin/ I would assume if a canister was added for noise levels there would be some additional weight on the nose.
As for the airplanes you are looking at, all I can say is both companies would be on my short list for ARF's that I would recommend and both are run by some great people.